The present invention relates generally to mechanical fasteners and more particularly to mechanical fasteners used in conjunction with shims.
A rear wheel drive vehicle typically includes a transmission having an output shaft connected through an elongated driveshaft to an axle assembly. The driveshaft typically comprises two or more propeller shafts which are connected with a universal joint.
One of the propeller shafts is supported by a center bearing secured to the underbody of the motor vehicle. The driveline is positioned for proper orientation and alignment by placing shims or washers during installation between the center bearing and underbody.
Various mounting and positioning schemes are disclosed in the prior art for insuring driveline propeller shaft alignment with the center bearing and the vehicle body. Currently, manufacturers use washers to shim propeller shafts. However, the use of loose shims or washers is cumbersome in the assembly plant environment.
U.S. Pat. No. 5,469,931 to Kawata et al. describes an attachment means provided by engaging serrations and a locking nut for connecting and aligning the propeller shafts with the center bearing. U.S. Pat. No. 5,829,892 to Groves discloses a center bearing collar assembly having a bearing race with a rigid fixed mounting scheme requiring washer shims to provide incremental changes in vertical alignment.
U.S. Pat. No. 5,314,380 to Yamamoto teaches an improved structure of a universal joint for reducing swing torque having a spider axially rotated on a bearing cup with no shim means provided for self-retaining to the floor pan. U.S. Pat. No. 5,452,548 to Kwon also teaches a bearing structure with an isolation and anchor device for supporting bridges and other vertical structures formed with a multilayer pattern of metal plates and bars located in the center bearing unit to improve vertical resistance as well as horizontal and torsional rigidity.
U.S. Pat. No. 5,703,796 to Moradi et al. relates to an apparatus and method for aligning a driveline in a motor vehicle by positioning a center bearing to the body of the motor vehicle to further support the driveshaft. The position of the driveline is then measured and a shim thickness is calculated for installation between the center bearing and the body. None of the five recited prior art patents either teach or disclose the subject invention shim carrier assembly and self-retaining feature.
The present invention overcomes the prior art disadvantages by providing self-retaining attachment means between the driveline, center bearing, and underbody when the propeller shaft assembly is installed to the vehicle. The self-retaining attachment means is provided with a shim stock common carrier of various shim thicknesses for proper alignment. Without the common carrier and self-retaining feature, shims must be placed over each stud while the propeller shaft is being attached to the vehicle underbody.
It is an object of the present invention to minimize the number of sub-component shims by allowing shim stock of various thicknesses to be assembled into a common carrier. This overcomes an inherent disadvantage in prior art attachment schemes for mounting the propeller shaft and center bearing assembly to the propeller attachment studs in the floorpan. Without the common carrier and self-retaining shim stock feature of the present invention, shims must be manually placed over each stud while the propeller shaft and center bearing assembly is being attached to the underbody.
The common shim carrier assembly slides onto the propeller shaft center bearing to allow the propeller shaft center joint to operate at the desired orientation. This is achieved because the shims are positioned between the propeller shaft center bearing and the body when the propeller shaft is installed to vehicle floorpan. Ultimate retention of the shim carrier is achieved with the fasteners that hold the propeller shaft to the body.
The present invention overcomes the disadvantages of the prior art approaches and simplifies the attachment schemes by providing a common shim carrier formed from malleable sheet metal or other material preferably in a substantially flattened xe2x80x9cIxe2x80x9d shape having three layered intercontiguated planar portions, generally parallel to one another and provided with holes or slots for attachment and alignment through the three planar portions.
Other features, objects, and advantages of the present invention will be become apparent from the following detailed description of the drawings, the preferred embodiments, and the claims.